A Total Synthesis of Galbonolide B

An ester enolate rearrangement/silicon mediated fragmentation cascade was used to convert <b>7</b> and <b>8</b> into the alcohol <b>9</b>.
The alcohol <b>9</b> was converted into the allylic alcohol <b>12</b> and
then to the ester <b>14</b>. A further ester enolate rearrangement
furnished the stereochemical identity of galbonolide B <b>1</b>.
Base mediated macrocyclization of the acetate ester <b>16</b>
followed by base mediated alkylation and acetal deprotection
gave galbonolide B <b>1</b>.